Technology Trends

In Europe DVB-T2 has been deployed in several countries for HD services. ATSC is used in USA, Canada, Mexico, and Korea, while ISDB-T is employed in Japan, Uruguay, and Brazil.

2. Digital terrestrial radio broadcasting

In Europe and Asia DAB+ is state of the art in the DAB Eureka 147 family. HD-Radio or IBOC fulfils this role in the USA and Canada. Large broadcasting organizations in Europe and Asia, and major countries like India and Russia with large potential audiences, are committed to the introduction of DRM (Digital Radio Mondiale) services and it is to be expected that this will open the market for low-cost receivers.

3. Digital terrestrial TV broadcasting for mobile receivers

DVB-T2 Lite has been standardized and chip-sets are available, while ISDB-T is used in Japan. DMB is employed in Korea and there have been a few trials in Europe. In the USA, the Advanced Television Systems Committee (ATSC) has begun development of a non-backwards compatible system with next-generation video compression, transmission and Internet Protocol technologies via local broadcast TV stations. This effort is termed “ATSC 3.0” and is covered in some detail within the professional journals and the industry trade press. It is too early to fully characterize the eventual results.

4. Benefits of digital broadcasting

The introduction of digital broadcasting has introduced such benefits as High Definition TV (1080i, 720p). Due to the current availability of 5.1 surround sound in digital broadcasting, surround sound is an important trend in TV broadcasting. 5.1 surround sound is evolving with future extensions involving additional channels. Along with Ultra-High Definition image (4k video), several broadcasters are experimenting with immersive audio (for instance, 3D-multichannel-audio, Ambisonics, wave-field synthesis, directional audio coding).

5. Internet streaming

The use of new methods for the distribution of signals to the home via the Internet with streaming services is an increasing trend. Web radio and IPTV are now getting audience figures that in a number of years from now will be closing in on the traditional systems. Distribution technologies with rapid growth in many countries are: ADSL/VDSL over copper or fiber, combined with WiFi in homes; WIMAX and 3G/UMTS; 4G and wi-fi hot spots for distribution to handheld devices.

6. Loudness

Loudness and True Peak measurements are replacing the conventional VU/PPM methods of controlling program levels. This has largely eliminated significant differences in the loudness of different programs (and advertisements) and the need for listeners to keep adjusting their volume controls. Supporting international standards and operating practices have been published by several organizations such as ITU-R, EBU and ATSC listed below. More and more broadcasters now apply these standards in their program production and transmission chains.

The fundamental document upon which all other work was based is ITU-R: BS.1770: “Algorithms to measure audio programme loudness and true-peak audio level”; BS.1771: “Requirements for loudness and true-peak indicating meters”. Importantly, it not only documents loudness but a standardized method to measure true peak in digital audio streams. This is a vital, and often overlooked aspect, as the loudness measurement is a time averaged value which should not be changing rapidly. So the operator needs a reliable method of ensuring they are not clipping their signals. The true peak provides this method.

Starting roughly a year after the ATSC drafting group, the EBU drafting group has produced a similar set of documents:

- EBU R128 Loudness Recommendation

- EBU Tech 3341 Metering specification

- EBU Tech 3342 Loudness Range descriptor

- EBU Tech 3343 Production Guidelines

- EBU Tech 3344 Distribution Guidelines

EBU has, beyond minor revisions of R128 and its belonging Tech docs, a major deliverable planned for 2015 concerning the revision of the loudness range algorithm (Tech 3342).

The seeming “disconnect” between A/85 and the R128-family can be best understood by the very different scopes of each documents. A/85 is focused on DTV audio only, while R128 attempts to cover almost any audio delivery mechanism (seemingly including analog). Beyond the seeming differences between A/85 and R128, the US Congress adopted a seemingly simple, but with unintended consequences, law called CALM (“Commercial Advertisement Loudness Mitigation Act”). Free TV Australia produced Operational Practice OP–48 (which the Australian Government made mandatory also). ARIB in Japan has issued. TR-B32 1.2 “Operational Guidelines for Loudness of Digital Television Programs.”

7. Object-based audio

"Object-based audio" is currently the subject of great interest in the EBU, ITU, AES and SMPTE. At its heart is the meta-data describing the audio content that will enable its correct handling along the broadcast chain, and optimal rendering for the individual listener. As part of this, the EBU has produced the "Audio Definition Model", published in EBU Tech Doc 3364, (which is currently the subject of standardization activities in the ITU). In the ITU-R there are two relatively recent publications outlining the future: Report ITU-R BS.2266 "Framework of future audio broadcasting systems", and “Recommendation ITU-R BS.2051 "Advanced sound system for programme production."

8. Immersive audio

EBU FAR strategic programme group has founded a work group for 3D audio, renamed Immersive Audio. Object-based production embraces all these new technology trends below:

- 3D audio production

- 3D audio codecs

- 3D audio broadcasting

- 3D audio file formats

- 3D audio creativity

The MPEG Committee has begun work on “immersive sound” coding.

9. Audio/Video (“Lip”) sync

The audio/video-sync issue remains unsolved, but is being discussed in digital broadcasting groups. SMPTE is close to issuing new standards for measuring the time differences between audio and video.

Meeting Report:

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Technical Report:

2015-6-20 Study of Audio Loudness Range for Consumers in Various Listening Modes and Ambient Noise LevelsDescription: An algorithm for an intelligent loudness manager. Most listeners do not want zero loudness range (they appear to understand that audio has natural variation in loudness), even in noisier environments. Similarly, they didn’t maintain a constant audio “SNR” relative to the environmental noise level, raising the playback less for every dB increase in environmental noise. These are positives for the quality-conscious engineers who want to maintain (or return to) wider dynamics. The CEA’s Audio Systems Committee is considering making the results a CEA standard.